Subdural hematoma in infants without accidental or nonaccidental injury: benign external hydrocephalus, a risk factor.

Benign external hydrocephalus (BEH) is considered a self-limiting condition in infants. Subdural hematoma (SDH) in infants without a history of trauma indicates nonaccidental injury (NAI). The authors studied whether SDH can complicate BEH without apparent trauma. Out of 45 children younger than 3 years with nontraumatic SDH, 9 (7 boys) with mean age 6 months had BEH as risk factor. Symptoms included increasing head size (8), fussiness, and irritability (3). Three had up-gaze restriction, 1 axial hypotonia, and 6 normal examination. Neuroimaging showed prominent extra-axial spaces; SDH was bilateral (6), subacute (5). Other etiological workup for SDH was negative except NAI in 1. Two required evacuation of SDH and subdural-peritoneal shunt; others managed conservatively. Development was normal in 8 on follow-up. On follow-up imaging of 8, SDH completely resolved in 3, markedly reduced in 3, and remained stable in 2. BEH is a risk factor for SDH in infants, thus not always benign.